Antifouling paints are well known for use in coating the surface of the submarine parts of a ship's hull in order to protect them from fouling resulting from the growth of marine organisms on the surface. Typically, an antifouling paint contains an antifouling agent which can be freed from the surface of the paint to the marine organisms accumulated on the hull surface by concentration gradient. Self-polishing type antifouling paints are gradually dissolvable in seawater to continuously reveal, over a period, a fresh anti-fouling paint surface which permits release of the antifouling agent. Such self-polishing type antifouling paints contain a film-forming resin which is hydrolyzable by seawater.
Metal soaps prepared by reacting high hydrophobic saturated fatty acids such as naphthenic acid with a compound of a multi-valent metal such as Co, Mn, Zn, Cu or Ca are commercial products well known as driers and catalysts for paints. The metal soaps produced from such saturated fatty acids do not function as a film-forming binder.
U.S. Pat. No. 2,423,044 discloses a hydrolyzable resin composition which comprises an acrylic resin having at least one side chain bearing at least one metal ester containing terminal group. The patent suggests use of monovalent organic acids to react with a metal compound for the formation of the metal ester containing terminal group. The monovalent organic acids as disclosed are saturated organic acids including saturated fatty acids.
The basic U.S. application of this application discloses a self-polishing type antifouling coating composition which comprises a metallic soap compound prepared by reacting a metal compound containing a metal having a valency of at least 2 with at least an unsaturated fatty acid or alcohol. The metallic soap compound formed thereby is used as a film-forming binder for the coating position.